Douglas Harper's Etymology Dictionary
lesbo
by 1940, colloquial shortening of lesbian.
Wiktionary
lesbo
n. (context colloquial English) lesbian.
Usage examples of "lesbo".
The paper didn't identify these last, but Norman already knew one of them: Daughters and Sisters, also known as Lesbo Babes in Toyland.
So I told Bridget everything that had happened, from Marcus's invitation to Burke's lesbo comment to the bit lip.